RESUMEN
BACKGROUND: Among superficial neoplastic lesions of the colon and rectum, a laterally spreading tumor (LST) is a flat elevated type at least 10 mm in size. It can be treated by conventional endoscopic resection (CER). Nevertheless, local residual neoplasia (LRN) may occur during follow-up. The aim of this prospective study was to evaluate the occurrence of LRN and the risk factors for its presence. METHODS: Consecutive patients referred for CER of an LST were included. Follow-up colonoscopies were performed after 3 and 15 months. LRN was defined histologically as the presence of neoplastic tissue in the post-CER site. RESULTS: Of a total of 127 patients with 127 lesions, follow-up could not be completed in 48 (37.8%). Of the remaining 79 (62.2%) patients (64.6% men, mean age 66.1±9.7 years), 63 (79.7%) were negative and 16 (20.3%) were positive for the presence of LRN after 15 months. Of 62 (78.5%) patients without LRN after 3 months, 55 (88.7%) remained negative after 15 months. Of 17 (21.5%) patients with LRN after 3 months, eight (47.1%) were negative after 15 months. In a multivariate analysis, LST size of at least 20 mm was found to be a significant risk factor after 3 months (odds ratio, 5.837; 95% confidence interval 1.199-28.425; P=0.029). After 15 months, the only significant risk factor was the presence of LRN observed after 3 months (odds ratio, 6.0; 95% confidence interval, 1.793-20.073; P=0.004). CONCLUSION: This prospective study shows that the occurrence of LRN is frequent and its treatment is less effective than reported previously. These are important limitations of CER and should be taken into consideration for the management of patients with LSTs.